WO2000060910A1 - The method and the apparatus for plasma generation - Google Patents

The method and the apparatus for plasma generation Download PDF

Info

Publication number
WO2000060910A1
WO2000060910A1 PCT/RU1999/000428 RU9900428W WO0060910A1 WO 2000060910 A1 WO2000060910 A1 WO 2000060910A1 RU 9900428 W RU9900428 W RU 9900428W WO 0060910 A1 WO0060910 A1 WO 0060910A1
Authority
WO
WIPO (PCT)
Prior art keywords
initiator
resonator
discharge chamber
microwave
disposed
Prior art date
Application number
PCT/RU1999/000428
Other languages
French (fr)
Inventor
Jury Vladimirovich Korchagin
Original Assignee
Jury Vladimirovich Korchagin
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Jury Vladimirovich Korchagin filed Critical Jury Vladimirovich Korchagin
Priority to AU13013/00A priority Critical patent/AU1301300A/en
Publication of WO2000060910A1 publication Critical patent/WO2000060910A1/en

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/32—Gas-filled discharge tubes
    • H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
    • H01J37/32192—Microwave generated discharge
    • H01J37/32211—Means for coupling power to the plasma
    • H01J37/32247—Resonators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/32—Gas-filled discharge tubes
    • H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
    • H01J37/32357—Generation remote from the workpiece, e.g. down-stream
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H1/00—Generating plasma; Handling plasma
    • H05H1/24—Generating plasma
    • H05H1/26—Plasma torches
    • H05H1/30—Plasma torches using applied electromagnetic fields, e.g. high frequency or microwave energy
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H1/00—Generating plasma; Handling plasma
    • H05H1/24—Generating plasma
    • H05H1/46—Generating plasma using applied electromagnetic fields, e.g. high frequency or microwave energy

Definitions

  • the present invention pertains to plasma technology, or more specifi ⁇
  • the microwave plasma generation devices contain a micro ⁇
  • waveguide can be used as such volume.
  • Such devices require special means to initiate a plasma arc, e.g. re-
  • an initiator is disposed in the plasma gen ⁇
  • odic element is identified in the discharge pattern.
  • the plasma-generating zone has a shape identical to that of the periodic
  • ric shape of the initiator is chosen to coincide with the discharge pattern.
  • the initiator Besides, once a gas or the gas pressure are changed, the initiator
  • the main goal of the invention is to ensure a stable and reliable dis ⁇
  • a low-power microwave source are utilizing the intensity of the
  • This method to generate plasma is according an apparatus compris ⁇
  • the apparatus is complemented by a cavity resonator and the initiator is
  • crowave magnetron being disposed inside of the cavity resonator.
  • end of the initiator disposed in the resonator is oriented parallel to the di-
  • the initiator can be made in such way that the end of the
  • initiator disposed in the resonator is either connected or not connected with
  • the length of the initiator satisfies the following equation:
  • L - is the total length of the initiator
  • ⁇ - is the microwave length in a free space
  • the initiator can be of virtually any shape but for the sake of
  • the metal initiator can also be constructed as two connected perpen ⁇
  • the initiator can be made in the form of a tube. Disposed in the reso ⁇
  • nator cavity is the one end of the tube while the other end is brought out
  • the discharge chamber can be made as a
  • the resonator is connected with
  • the initiator is disposed in the antinodes of the
  • a microwave magnetron is used as a microwave source.
  • sources are used for plasma generation.
  • the field intensity should be raised to a required level prior to
  • a cavity resonator can be used for
  • a cavity resonator can be utilized to tune and stabilize a magnetron
  • the oscillations are excited at the resonant frequency of the mag ⁇
  • microwave magnetron element being located in the resonator.
  • the initiator is disposed in the plasma generation area.
  • the initiator is therefore disposed both in the
  • This working mode can be sustained if there is a high quality factor
  • the cavity resonator and a standing wave is formed with the maxim and
  • nodes is much higher than the magnetron field intensity in a free space.
  • the initiator being located in the resonator and discharge
  • chamber cavities ensures that there is virtually no microwave radiation
  • the shape and dimensions of the discharge chamber determine the shape and dimensions of the discharge chamber
  • the microwave magnetron tunes itself onto a frequency correspond ⁇
  • the magnetron tunes to this frequency.
  • the microwave energy is transferred to the plasma-burning zone
  • the apparatus work as a whole.
  • the discharge is automatically initialized
  • the discharge can be obtained in the air at atmospheric pressure and does not
  • Fig. 1 shows the ap ⁇
  • Fig.3 shows the apparatus version where the initiator is made as
  • Fig.4 shows the appa-
  • Fig.5 shows the apparatus version
  • the apparatus contains a microwave magnetron 1 , with a radiating
  • the end of the initiator 5 is located in a discharge
  • the apparatus works in the following way.
  • 300 tiator 4 - discharge chamber 6 system is set within a very short time ( ⁇ 10 ⁇ 8
  • a discharge sets in the vicinity 5 of the initiator 4 and devel ⁇
  • oping plasma absorbs the energy radiated by the radiating element 3 of the
  • the nozzle 7 and the dielectric tube 8 along with the gas supply system form a plasma jet. If the discharge extinguishes the initi ⁇
  • L is the total length of the initiator
  • ⁇ is the length of the microwave in free space
  • n 1 , 2, 3 ...
  • the initiator can be made as a linear conductor parallel to the electric
  • electric field antinode parallel to electric field vector is ⁇ /4.
  • the metal initiator can be made as a tube one end of the tube electri ⁇
  • ⁇ 0 - is the microwave radiation angular frequency
  • V is the resonator volume, chosen to be V ⁇ ⁇ " '
  • the electric field strength will be E () - 160 kV/cm.
  • the discharge chamber was constructed as a cylinder coaxial sur-
  • the plasma jet temperature reached a 4500°C level.
  • the apparatus works very stable, and in case of a plasma extinguish ⁇
  • plasmatron can operate from normal mains.
  • the apparatus is very compact and simple; there are no me-
  • this device is relatively small and makes it

Abstract

The present invention relates to a plasma technology and can be used in low-power and movable plasma generating microwave devices. A method based on initiation of a discharge in a gas medium by means of electromagnetic microwave for utilizing a low-power microwave source the intensity of the electromagnetic field is increasing. An apparatus for realization of this method containing a microwave source, a gas-filled discharge chamber with a conducting initiator disposed in the chamber. The apparatus differs from the like devices for it is complemented by a cavity resonator and the initiator disposed simultaneously in the discharge chamber and the resonator. One end of the initiator disposed in the discharge chamber is located in the antinode area of the standing wave which forms in the discharge chamber while the other end is disposed in the antinode area of the standing wave being formed in the resonator. A microwave magnetron serves as a microwave source. The magnetron radiating element is disposed within the cavity resonator with a resonant frequency corresponding to that of the microwave magnetron working frequency.

Description

THE METHOD AND THE APPARATUS
FOR PLASMA GENERATION.
TECHNICAL FIELD
The present invention pertains to plasma technology, or more specifi¬
cally to the means of plasma generation using external microwave electro-
magnetic fields, and can be utilized in low-power easily portable plasma
inducing microwave devices, which can be used in various fields such as,
for example, plasma metal surface processing, ecological purification of
industrial and domestic waste, medical and biological applications etc.
PRIOR ART
In order to efficiently use microwave-induced plasma it is most im¬
portant to ensure its stability at the least possible electric field intensity
both for impulse and continuous generation modes. The lack of stability in
plasma generation makes it technologically unusable. Also, using high in¬
tensity electric fields results in powerful yet costly microwave devices with short lifetime, requiring isolated boxes to protect personnel from
microwave radiation.
25 Usually, the microwave plasma generation devices contain a micro¬
wave source (magnetron), a waveguide to transmit power to the volume
where plasma is generated and maintained. [πopomicoBaa Meτajuιypιιιa H
*
HaribiJieHHe πoκpbiτHH. o χ pe,n. πpoφ. B.C. MHTHHa, «MeτaJiJiyprHfl»,
1987, c.c. 631 -635; US patent M. 4370539, Lnt.Cl.6 B23 K 9/16, filed.
30 07.10.80, publ. 25.10.83; US patent N_ 5210392, Int.Cl.6 B23 K 9/00, filed.
07. 1 1.90, publ. 1 1.05.93]
A vacuum chamber, resonator, or just a tube intersecting with the
waveguide can be used as such volume.
Such devices require special means to initiate a plasma arc, e.g. re-
35 ducing the gas pressure to a breakdown level, bringing the electrodes
closer, external spark to the plasma generation volume or direct shorting
the electrodes. This allows obtaining repeated initiation but leads to a rapid
destruction of electrodes.
The plasma in such devices is unstable and if it extinguishes a new
40 external initiation of the arc is required.
Besides, these apparatus are quite big and require auxiliary devices
such as vacuum system, power installation to achieve a high field intensity
and special means to protect from a microwave emission. Another method for plasma generation uses high
intensity microwave in a gas to initiate a discharge and generate plasma. A
stable plasma generation in the gas takes place when the electric field of
microwave reaches the discharge threshold. [CB -paspa^ BLICOKOΓΌ #aB-
jieHHΛ B πyιικax 3JieκτpoMarHHTHbix BOJIH. CGopHHK Hayιmbix Tpyjr B ΠOΛ
pea. Jl.r. JlHTBaκa. TopbKHH, 1988, c.c. 141-142].
To implement this method an initiator is disposed in the plasma gen¬
eration zone. The presence of the initiator reduces the plasma generation
threshold by several times depending on the gas pressure. At the same time
the space and time stability of the microwave discharge reproduction are
quite often appeared to be insufficient.
Another way of plasma generation entails the following: An initial¬
ized discharge is created in a gas by means of a microwave. Then a peri¬
odic element is identified in the discharge pattern. The initiator disposed in
the plasma-generating zone has a shape identical to that of the periodic
element identified in the discharge pattern. The corresponding device in¬
cludes the magnetron, the discharge chamber, and an initiator. The geomet¬
ric shape of the initiator is chosen to coincide with the discharge pattern.
[Patent RU 2046559, Int.Cl.6 H05H 1/46, filed. 30.12.92, publ. 20.10.95, Jfc
29]. This method allows reducing substantially the breakdown
threshold. But if the gas pressure in the discharge chamber is of the order or
higher then the atmospheric one, a very high electric field intensity, and
consequently a very high power supply is required to initialize the dis¬
charge.
Besides, once a gas or the gas pressure are changed, the initiator
shape should also be changed, which makes it quite difficult to use.
INVENTION DISCLOSURE
The main goal of the invention is to ensure a stable and reliable dis¬
charge generation to form a continuous plasma flow in any gas environ¬
ment under any gas pressure by means of automatically plasma initiation
using low-power microwave sources.
This goal is achieved by the method for plasma generation based on
initiation of a discharge in a gas medium by means of electromagnetic mi¬
crowave, a low-power microwave source are utilizing the intensity of the
electromagnetic field is being increased for which purpose a cavity reso-
nator is being used and strong coupling between the microwave source and
the said resonator is being established, and comprising the steps of exciting
oscillations at the frequency corresponding to the resonant frequency of the system including the microwave source and the
90 resonator, determining the antinodal regions of the standing wave and the
direction of the electric vector oscillations in the resonator connected with
the discharge chamber with strong coupling being established between
them, analyzing the electromagnetic field pattern in the discharge chamber
by positioning the antinodal regions, disposing the initiator in the antinodal
95 region of the resonator and the discharge chamber and aligning the said
initiator with respect to the direction of the electric vector oscillations in
the resonator and then exciting oscillations at the frequency corresponding
to the resonant frequency of the system: microwave source-resonator-
initiator-discharge chamber, while increasing the electromagnetic field in-
100 tensity to the magnitude exceeding the breakdown level for the gas filling
the discharge chamber and thereby initiating a discharge and generating
plasma by means of microwave radiation.
This method to generate plasma is according an apparatus compris¬
ing a microwave source, a gas-filled discharge chamber and an initiator
105 made of conducting material and disposed therein, and differing by the fact
that the apparatus is complemented by a cavity resonator and the initiator is
disposed in both the discharge chamber and the resonator, the initiator end
in the discharge chamber being disposed in the antinodal region of the standing wave generated inside of the discharge chamber,
while the other end being disposed in the antinodal region of the standing
wave generated inside of the resonator and the microwave source is a mi-
115 crowave magnetron the working frequency of which corresponds to the
resonant frequency of the cavity resonator, the radiating element of the mi¬
crowave magnetron being disposed inside of the cavity resonator.
The optimum electric field intensity increase can be reached if the
end of the initiator disposed in the resonator is oriented parallel to the di-
120 rection of the electric vector oscillations.
In this case the initiator can be made in such way that the end of the
initiator disposed in the resonator is either connected or not connected with
its conducting surface, its diameter in the latter case being at least two
times larger than the diameter of the initiator's end disposed in the dis-
125 charge chamber. The length of the initiator satisfies the following equation:
L = nλ/2 + λ/4 ( 1 ),
where
L - is the total length of the initiator;
λ - is the microwave length in a free space;
130 n - is 1 ,2,3 ... The initiator can be of virtually any shape but for the sake of
convenience it can be made as a linear conductor or a curved conductor, for
example, as a U-shaped current loop, the section of this current loop con-
135 necting its parallel sections being located in the antinode of the standing
wave set in the resonator and parallel to the electric field. This section
length is λ/4.
The metal initiator can also be constructed as two connected perpen¬
dicular straight line sections, the length of the section disposed in the reso-
140 nator parallel to the electric field is λ/4.
When using the device for plasma spray coating, e.g. to a cutting
edge, the initiator can be made in the form of a tube. Disposed in the reso¬
nator cavity is the one end of the tube while the other end is brought out
and connected to the gas supply.
145 To form a plasma jet, the metal initiator's end located in the discharge
chamber can be fitted with a high-melting metal nozzle. Alternatively, in¬
stead of a metal nozzle, it is possible to put a dielectric tube made of a
high-melting dielectric material with a low microwave energy loss, e.g. of
quartz.
150 To simplify assembling, the discharge chamber can be made as a
cylinder coaxial surrounding a part of the initiator. Comparative analysis has shown, that the solution presented is
different in that the oscillations are excited at the frequency corresponding
155 to the resonant frequency of the system consisting of the microwave source
and the resonator. The antinodes of the standing wave and the electric vec¬
tor oscillation direction are identified. The resonator is connected with
the discharge chamber. The initiator is disposed in the antinodes of the
resonator and the discharge chamber and is oriented with respect to the
160 electric vector oscillations in the resonator.
A microwave magnetron is used as a microwave source. The initiator
is disposed in the resonator cavity and in the discharge chamber.
The essence of the invention is as follows:
It is well known that the intensity of the electric field required to ini-
165 tiate a discharge is by several orders of magnitude higher than that to sus¬
tain already initiated discharge. Therefore sufficiently powerful microwave
sources are used for plasma generation.
If a low-power microwave source is used, a microwave magnetron
for example, the field intensity should be raised to a required level prior to
170 the discharge initiation To do this the apparatus should be complemented
by a microwave energy accumulator. A cavity resonator can be used for
this purpose. 175 There is however a problem of how to tune the resonator
and the microwave generator to the same resonant frequency.
A cavity resonator can be utilized to tune and stabilize a magnetron
frequency. In this case additional resonate states appear in the magnetron
resonance system regardless of the way the magnetron anode block is cou-
180 pled with the resonator. [ LB. CaMCOHOB. "OCHOBU pacιιeτa H
KOHCTpynpoBaHHH MaraeTpoHOB", M., 1974, c.c. 167- 194].
According to the "minimum dissipation" principle, the "magnetron-
resonator" system oscillations are excited at the frequency where the ratio
of the energy conserved to the total loss energy over a period reaches its
185 maximum. This is a maximum quality factor frequency. Since the magne¬
tron resonance system quality factor is much less than that of the cavity
resonator, the oscillations are excited at the resonant frequency of the mag¬
netron-resonator system. Naturally this frequency should be fairly "close"
to the magnetron working frequency. The degree of closeness depends on
190 the magnetron type and how strongly it is connected with the resonator.
This means that if the magnetron is strongly linked with the cavity
resonator and their frequencies coincide to an accuracy of not more than 10
percent, the oscillations will be excited at the resonant frequency of the
system without any mechanical tuning elements. Such a strong link is provided due to the radiating
microwave magnetron element being located in the resonator.
To make the plasma generation threshold lower and reducing power
level, the initiator is disposed in the plasma generation area. The initiator
200 also provides a strong link in the system microwave magnetron - resonator
and the discharge chamber. The initiator is therefore disposed both in the
resonator and the discharge chamber cavities.
This working mode can be sustained if there is a high quality factor
of the whole system, which includes the magnetron, the cavity resonator,
205 and the discharge chamber. To do this requires exclusion of all the energy
losses except those due to a finite conductivity of the resonator walls.
All these condition being met, the energy starts to accumulate within
the cavity resonator and a standing wave is formed with the maxim and
minim of electric field spaced depending on the specific cavity resonator
210 type (cylindrical, coaxial, rectangular, etc.) and the type of the oscillation
excited.
In this situation, the electric field intensity in the standing wave anti-
nodes is much higher than the magnetron field intensity in a free space. For
high quality factor resonators such an intensity increase can be very high,
215 up to 100 and more. The initiator being located in the resonator and discharge
chamber cavities ensures that there is virtually no microwave radiation
220 from the discharge chamber into outer space at the pre-discharge stage and
that there is a strong link between the resonator and the discharge chamber
which results in a standing wa e being formed inside the discharge cham¬
ber.
The shape and dimensions of the discharge chamber determine the
225 spatial distribution of the electric field antinodes.
Usually when a cavity resonator is used to achieve a microwave
breakdown level, a gas discharge which forms when intensity reaches a
breakdown level, spreads over the whole resonator volume.
Numerous experiments have shown that if the initiator end located in
230 the discharge chamber coincides with the standing wave antinode, the dis¬
charge takes place at this end, i.e. where there is a maximum inhomogenity
of the field.
After being initiated the discharge locates itself near the initiator's
end and does not spread to other areas of the discharge chamber or the
235 resonator.
Since the other end of the initiator disposed in the iesonator is located
in the high field intensity area special measures should be taken to avoid
the discharge formation in this end vicinity. One of the options is to make 240
the diameter of this end of the initiator at least two times larger compared
to that of the other end which is located in the discharge chamber.
Increasing the diameter allows reducing the field gradient in the vi¬
cinity of the initiator surface and to increase the field intensity required for
245 the gas breakdown in the resonator, i.e. increasing the breakdown voltage
of the resonator.
The presence of the initiator and discharge chamber changes slightly
the fundamental resonant frequency of the magnetron - cavity resonator
system. Nevertheless, the quality factor of the magnetron, resonator, ini-
250 tiator, and the discharge chamber system remains high, since there is virtu¬
ally no radiation from the system.
The microwave magnetron tunes itself onto a frequency correspond¬
ing to the resonant frequency of the magnetron-resonator-initiator-
discharge chamber system.
255 After the discharge is excited the plasma starts to absorb energy,
which results in the system quality factor dropping sharply. If it becomes
advantageous in terms of energy for the magnetron to radiate oscillations at
its working frequency, the magnetron tunes to this frequency.
As the strong link being established between the magnetron and the
260 resonator on one hand and resonator and the discharge chamber on the other hand, the microwave energy is transferred to the plasma-burning zone
effectively.
265 If due to some reasons the discharge dies out, the whole system qual¬
ity factor reinstates very fast, and the discharge reappears. The time interval
for the discharge to restore is so small (~10" sec) that it does not influence
the apparatus work as a whole. The discharge is automatically initialized
which allows getting a stable self-initializing plasma discharge.
270 The discharge can be obtained in the air at atmospheric pressure and does not
require a highly powerful microwave generator.
BRIEF DESCRIPTION OF THE DRAWINGS
275 The apparatus work is illustrated by the Figures. Fig. 1 shows the ap¬
paratus version where the initiator is made as a liner conductor, Fig.2
shows the apparatus version where the initiator is made as U-shaped cur¬
rent loop, Fig.3 shows the apparatus version where the initiator is made as
two perpendicular connected straight line sections, Fig.4 shows the appa-
280 ratus version where discharge chamber surrounds the initiator, the initiator
lies along the discharge chamber axis, Fig.5 shows the apparatus version
where the end of the initiator disposed in the resonator is not connected
with its conducting surface and its diameter is at least two times 285 larger than that of the end of the initiator disposed in the discharge cham¬
ber.
The apparatus contains a microwave magnetron 1 , with a radiating
element 2 placed inside a cavity resonator 3, an initiator 4 also placed in¬
side a cavity resonator. The end of the initiator 5 is located in a discharge
290 chamber 6. A nozzle 7 and a tube 8 made of a dielectric material with a
high melting temperature and low microwave radiation energy loss are put
on this end of the initiator. The other end of the initiator 9 is brought out of
the resonator cavity and connected to a gas supply, dl and d2 are the di¬
ameters of the ends of the initiator disposed respectively in the discharge
295 chamber 6 and the resonator 3 (Fig.5).
Description of the preferred embodiments
The apparatus works in the following way.
After the voltage is supplied to the magnetron 1 a frequency corre¬
sponding to the resonant frequency of the magnetron 1 - resonator 3 - ini-
300 tiator 4 - discharge chamber 6 system is set within a very short time (~10~8
sec).
Then energy builds up and within ~ 10~ ' sec reaches a breakdown in¬
tensity level. A discharge sets in the vicinity 5 of the initiator 4 and devel¬
oping plasma absorbs the energy radiated by the radiating element 3 of the
305 magnetron 1. The nozzle 7 and the dielectric tube 8 along with the gas supply system form a plasma jet. If the discharge extinguishes the initi¬
ating process repeats automatically.
Since the initiator provides at the same time a strong link between the
310 resonator and the discharge chamber, its dimensions must satisfy the fol¬
lowing requirement: it must provide optimum conditions for energy trans¬
fer to discharge zone after initiation. Numerous experiments have shown
that the best results are obtained if the initiator length is chosen to satisfy
the following equation:
315 L = nλ/2 + λ/4, ( 1)
where
L is the total length of the initiator;
λ is the length of the microwave in free space;
n = 1 , 2, 3 ...
320 The initiator can be made as a linear conductor parallel to the electric
field.
Since the location of the electric field antinodes within the discharge
chamber depends upon the shape and dimensions of the chamber and gen¬
erally does not coincide with the initiator's end, the initiator length
325 requires certain adjustment which in case of a linear initiator can contradict
the optimal initiator length requirement.
330 The ideal solution is the initiator made as U-shaped current loop or
two perpendicular straight line sections, in the latter case the length of the
section disposed in the resonator parallel to electric field vector is λ/4. The
optimum is reached when the length of the initiator section located in the
electric field antinode parallel to electric field vector is λ/4.
335 The metal initiator can be made as a tube one end of the tube electri¬
cally connected with the resonator surface being brought out through the
resonator wall and connected to the gas supply, in order to bring the plasma
into outer space.
To set the desired speed and shape of the plasma jet the end of the
340 initiator disposed in the discharge chamber can be fitted with a high-
melting nozzle. This prevents the end of the initiator from being destroyed
by high temperature plasma.
In order to form a plasma jet, a tube made of a dielectric material
with a high melting terr.peratuie and a low microwave energy loss, such as
345 of quartz, can be put on the initiator. Such a tube can be used if a nozzle is
put on the initiator end as well. Standard techniques can be applied to solve the problem of the high
350 temperature load onto the dielectric tube. This includes swirling the plasma
jet, external air-cooling, etc.
INDUSTRIAL APPLICABILITY
355 For typical cylinder resonators excited at the TM010 mode the field
intensity at the center of the resonator is, according to [McDonald, Micro¬
wave breakdown is gases]
Eo = Po Q / η ωo, (2)
where
360 Po - is the magnetron microwave radiation power;
Q - is the resonator quality factor;
ω0 - is the microwave radiation angular frequency;
η = 0.27-εo-V (3),
where
365 εn = 8.85- 10" " F / m - is the permittivity of free space;
V is the resonator volume, chosen to be V ~ λ" '
where λ is the length of the microwave in free space; 370 Using the equation (2) it is possible to choose a cavity resonator with
a relatively low quality factor (Q) reaching sufficiently high field strength
at the center of the resonator at the same time.
For example, when P„ = lkWt, ω0 / 2π = 2.45 GHz, V = l l, Q = 103
the electric field strength will be E() - 160 kV/cm. For example, the break-
375 down intensity for the air under atmospheric pressure is about
30 kV/cm.
EXAMPLE of USE
380 We used a magnetron with a power supply from a conventional microwave
oven with a power P = 800Wt and the frequency f = ω() / 2π = 2.45 GHz. It has
been thus possible to use the resonator made of copper with a volume V = 0.71 for
the wavelength λ = I 2cm.
The discharge chamber was constructed as a cylinder coaxial sur-
385 rounding the initiator with a titanium nozzle and a dielectric tube made of
quartz. The air under atmospheric pressure was used as a working gas.
The plasma jet temperature reached a 4500°C level. The process
lasting two hours, there were no plasma jet breaking or initiator erosion. 390
The apparatus works very stable, and in case of a plasma extinguish¬
ing the discharge is automatically initiated with low input power. Such a
plasmatron can operate from normal mains.
Besides, the apparatus is very compact and simple; there are no me-
395 chanically moving parts inside.
This makes it possible to use the apparatus in various fields such as
to solder virtually any kind of metal, even wolfram; to spray coat with
high-melting materials. Also this device is relatively small and makes it
possible to use it in medicine, dentistry, and jewelry art.
400
405
410

Claims

415 L A method for plasma generation based on initiation of a discharge
in a gas medium by means of electromagnetic microwave, differing by
utilizing a low-power microwave source the intensity of the electromag¬
netic field of which is being increased for which purpose a cavity resonator
is being used and strong coupling between the microwave source and the
420 said resonator is being established, and comprising the steps of exciting os¬
cillations at the frequency corresponding to the resonant frequency of the
system including the microwave source and the resonator, determining the
antinodal regions of the standing wave and the direction of the electric
vector oscillations in the resonator connected with the discharge chamber
425 with strong coupling being established between them, analyzing the elec¬
tromagnetic field pattern in the discharge chamber by positioning the an¬
tinodal regions, disposing the initiator in the antinodal region of the reso¬
nator and the discharge chamber and aligning the said initiator with respect
to the direction of the electric vector oscillations in the resonator and then
430 exciting oscillations at the frequency corresponding to the resonant fre¬
quency of the system: microwave source-resonator-initiator-discharge
chamber, while increasing the electromagnetic field intensity to the mag¬
nitude exceeding the breakdown level for the gas filling 435 the discharge chamber and thereby initiating a discharge and generating
plasma by means of microwave radiation.
2. An apparatus for plasma generation according to claim 1 com¬
prising a microwave source, a gas-filled discharge chamber and an initiator
made of conducting material and disposed therein, and differing by the fact
440 that the apparatus is complemented by a cavity resonator and the initiator is
disposed in both the discharge chamber and the resonator, the initiator end
in the discharge chamber being disposed in the antinodal region of the
standing wave generated inside of the discharge chamber, while the other
end being disposed in the antinodal region of the standing wave generated
445 inside of the resonator and the microwave source is a microwave magne¬
tron the working frequency of which corresponds to the resonant frequency
of the cavity resonator, the radiating element of the microwave magnetron
being disposed inside of the cavity resonator.
3. An apparatus according to claim 2, wherein the initiator end dis-
450 posed in the resonator is electrically connected with the conducting surface
of the resonator.
4. An apparatus according to claim 2, wherein the initiator end dis¬
posed in the resonator is not connected with the conducting surface of the
latter and the diameter thereof is at least twice as large as that of the initia-
455 tor end disposed in the discharge chamber.
5. An apparatus according to any one of claims 2 to 4, wherein the
initiator length is selected so that:
460 L= nλ/2+λ/4,
where
L is the total length of the initiator;
λ is the microwave length in the free space;
n=0, l ,2...
465 6. An apparatus according to any one of claims 2 to 5 with a straight
line initiator.
7. An apparatus according to any one of claims 2 to 5 with a curved
initiator.
8. An apparatus according to any one of claims 2 to 5 and 7, wherein
470 the initiator is made as a U-shaped coupling loop, the segment of the cou¬
pling loop connecting the parallel parts thereof being disposed in the anti¬
nodal region of the standing wave formed within the resonator and the
length of the said coupling loop segment being λ/4.
9. The apparatus according to any of the claims 2-5 and 7 which dif-
475 fers in that the initiator is curved as two perpendicular connected straight line sections, the length of section disposed in the resonator parallel to the
electric field is λ/4.
480 10. An apparatus according to any one of claims 2 to 9, wherein the
initiator is made as a tube and the end thereof disposed in the resonator
goes thereout and is connected with a gas supply system.
1 1. An apparatus according to any one of claims 2 to 5 and 7,
wherein the end of the initiator disposed inside of the discharge chamber is
485 fitted with a nozzle made of refractory material.
12. An apparatus according to claim 10 and/or 1 1 , wherein the ini¬
tiator end disposed inside of the discharge chamber is fitted with a tube
made of dielectric material with high melting temperature and low energy
losses on microwaves.
490 13. An apparatus according to claim 12, wherein the tube fitted over
the initiator end disposed inside of the discharge chamber is made of quartz
14. An apparatus according to claim 2-12, wherein the discharge
chamber is made as a cylinder coaxial with the part of the initiator disposed
therein.
495
PCT/RU1999/000428 1999-04-07 1999-11-11 The method and the apparatus for plasma generation WO2000060910A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU13013/00A AU1301300A (en) 1999-04-07 1999-11-11 The method and the apparatus for plasma generation

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
RU99106909 1999-04-07
RU99106909 1999-04-07
RU99110864A RU2171554C2 (en) 1999-04-07 1999-05-25 Method of plasma generation and device for its realization
RU99110864 1999-05-25

Publications (1)

Publication Number Publication Date
WO2000060910A1 true WO2000060910A1 (en) 2000-10-12

Family

ID=26654009

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/RU1999/000428 WO2000060910A1 (en) 1999-04-07 1999-11-11 The method and the apparatus for plasma generation

Country Status (3)

Country Link
AU (1) AU1301300A (en)
RU (1) RU2171554C2 (en)
WO (1) WO2000060910A1 (en)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002004930A1 (en) * 2000-07-06 2002-01-17 Varian Australia Pty. Ltd. Plasma source for spectrometry
EP1190605A1 (en) * 1999-05-11 2002-03-27 Daewon Paptin Foam Co., Ltd. Microwave plasma burner
FR2832022A1 (en) * 2001-11-06 2003-05-09 Christian Lincot High frequency electromagnetic wave generator includes magnetron in container with cooling system and waveguide for application to target
AU2001268845B2 (en) * 2000-07-06 2005-01-20 Agilent Technologies Australia (M) Pty Ltd Plasma source for spectrometry
WO2007086875A1 (en) * 2006-01-30 2007-08-02 Amarante Technologies, Inc. Work processing system and plasma generating apparatus
US9265138B2 (en) 2012-08-28 2016-02-16 Agilent Technologies, Inc. Electromagnetic waveguide and plasma source
CN116419464A (en) * 2023-06-09 2023-07-11 安徽农业大学 Plasma torch device

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2215061C1 (en) 2002-09-30 2003-10-27 Институт прикладной физики РАН High-speed method for depositing diamond films from gas phase in plasma of shf-discharge and plasma reactor for performing the same
WO2009128741A1 (en) * 2008-04-14 2009-10-22 Закрытое Акционерное Общество "Kotэc-Cибиpь" Uhf plasmotron
US8826983B2 (en) * 2010-12-29 2014-09-09 Schlumberger Technology Corporation Plasma charges
CN109761304A (en) * 2019-03-05 2019-05-17 成都科衡环保技术有限公司 Module, reactor and its application occur for the microwave plasma for water process

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3712971A1 (en) * 1987-04-16 1988-11-03 Plasonic Oberflaechentechnik G Method and device for producing (generating) a plasma
DE3905303A1 (en) * 1988-02-24 1989-08-31 Hitachi Ltd DEVICE FOR GENERATING A PLASMA BY MICROWAVE
DE3844034A1 (en) * 1988-07-05 1990-02-08 Mitsubishi Electric Corp DEVICE FOR MACHINING SEMICONDUCTOR DISCS USING A PLASMA PRODUCED BY ELECTRON CYCLOTRON RESONANCE
RU2046559C1 (en) * 1992-12-30 1995-10-20 Вадим Генадиевич Бровкин Method for plasma generation and device for implementation of said method

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3712971A1 (en) * 1987-04-16 1988-11-03 Plasonic Oberflaechentechnik G Method and device for producing (generating) a plasma
DE3905303A1 (en) * 1988-02-24 1989-08-31 Hitachi Ltd DEVICE FOR GENERATING A PLASMA BY MICROWAVE
DE3844034A1 (en) * 1988-07-05 1990-02-08 Mitsubishi Electric Corp DEVICE FOR MACHINING SEMICONDUCTOR DISCS USING A PLASMA PRODUCED BY ELECTRON CYCLOTRON RESONANCE
RU2046559C1 (en) * 1992-12-30 1995-10-20 Вадим Генадиевич Бровкин Method for plasma generation and device for implementation of said method

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1190605A1 (en) * 1999-05-11 2002-03-27 Daewon Paptin Foam Co., Ltd. Microwave plasma burner
EP1190605A4 (en) * 1999-05-11 2006-08-23 Daewon Paptin Foam Co Ltd Microwave plasma burner
WO2002004930A1 (en) * 2000-07-06 2002-01-17 Varian Australia Pty. Ltd. Plasma source for spectrometry
US6683272B2 (en) * 2000-07-06 2004-01-27 Varian Australia Pty Ltd Plasma source for spectrometry
AU2001268845B2 (en) * 2000-07-06 2005-01-20 Agilent Technologies Australia (M) Pty Ltd Plasma source for spectrometry
FR2832022A1 (en) * 2001-11-06 2003-05-09 Christian Lincot High frequency electromagnetic wave generator includes magnetron in container with cooling system and waveguide for application to target
WO2007086875A1 (en) * 2006-01-30 2007-08-02 Amarante Technologies, Inc. Work processing system and plasma generating apparatus
CN101361409B (en) * 2006-01-30 2011-09-14 赛安株式会社 Work piece processing system and plasma body generating apparatus
US9265138B2 (en) 2012-08-28 2016-02-16 Agilent Technologies, Inc. Electromagnetic waveguide and plasma source
CN116419464A (en) * 2023-06-09 2023-07-11 安徽农业大学 Plasma torch device

Also Published As

Publication number Publication date
RU2171554C2 (en) 2001-07-27
AU1301300A (en) 2000-10-23

Similar Documents

Publication Publication Date Title
US7589470B2 (en) Method and apparatus for producing plasma
USRE48317E1 (en) Interrupted particle source
Conrads et al. Plasma generation and plasma sources
US6917165B2 (en) Low power plasma generator
KR100291152B1 (en) Plasma generating apparatus
US4185213A (en) Gaseous electrode for MHD generator
JPH081830B2 (en) Microwave-powered processing system
EP2824998B1 (en) Plasma generation device with microstrip resonator
WO2000060910A1 (en) The method and the apparatus for plasma generation
US6734385B1 (en) Microwave plasma burner
WO2003039214A1 (en) Improved microwave stripline applicators
JP2004172044A (en) Microwave plasma generating device
US5580387A (en) Corrugated waveguide for a microwave plasma applicator
KR100832396B1 (en) A new electrodeless uv lamp
JPH11260593A (en) Plasma generating apparatus
CN112424901B (en) Low corrosion internal ion source for cyclotron
KR100500360B1 (en) High efficient-atmospheric microwave plasma system
JP2004087434A (en) Electrodeless discharge lamp light source equipment
WO2001001448A1 (en) Method and device for excitation and maintenance of a discharge in electrodeless lamp
RU2164048C1 (en) Device for microwave firing of gas-discharge laser and for lasing process maintenance by producing coaxial plasma line
JPH05299024A (en) Magnetron applied device
Vintizenko et al. Microwave radiation characteristics of relativistic magnetron with coupled cavities
JP2001357999A (en) Plasma generation device
JPH0653173A (en) Plasma processor having plasma heating mechanism
JPS6471099A (en) Plasma device

Legal Events

Date Code Title Description
ENP Entry into the national phase

Ref country code: AU

Ref document number: 2000 13013

Kind code of ref document: A

Format of ref document f/p: F

AK Designated states

Kind code of ref document: A1

Designated state(s): AL AU BA BB BG BR CA CN CU CZ EE GE HR HU ID IL IN IS JP KP KR LC LK LR LT LV MG MK MN MX NO NZ PL RO SG SI SK SL TR UA US VN YU

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): GH GM KE LS MW SD SL SZ TZ UG ZW AM AZ BY KG KZ MD RU TJ TM AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE BF BJ CF CG CI CM GA GN GW ML MR NE SN TD TG

121 Ep: the epo has been informed by wipo that ep was designated in this application
122 Ep: pct application non-entry in european phase